The Molecular Biology Division consists of a closely knit group of independent investigators, united by a common interest in the structure-function relations of membrane bound enzymes and in electron transport mechanisms. The present application is in support of the individual programs of three responsible investigators and of the core personnel and the facilities they share. The projected studies center around investigation of oxidation-reduction mechanisms, particularly in membrane-bound enzymes and in certain other flavoproteins. The research emphasis of the component projects is as follows: structure-function relations, biosynthesis and assembly of membrane bound respiratory enzymes; structure, kinetic mechanism and active site of flavoproteins, including flavocytochromes; molecular mechanism of fatty acid oxidation in heart; and structural elucidation of new covalently bound flavins and iron-sulfur clusters.